EVALUATION OF THE NEEDLE TECHNIQUE FOR PRODUCING AN ARTERIOVENOUS-FISTULA

The purposes of the present study were to evaluate the needle techniqu e of creating an arteriovenous (a-v) fistula and to quantitatively det ermine the hemodynamic responses in rats with three different fistula sizes. The fistula was made in male Sprague-Dawley rats between the ao rta and vena cava below the renal arteries by using 20-, 18-, and 16-g auge angiocath needles. Five weeks after a sham operation or creation of an a-v fistula, mean arterial blood pressure (MAP), right atrial pr essure, shunt flow, cardiac index, systemic flow, individual organ flo ws, and heart weight were quantitatively determined. All flow measurem ents were made using radioactive microspheres. The flow to the lungs w as used as a measure of shunt flow. The shunt flow in the 20-, 18-, an d 16-gauge fistula animals was significantly increased from a value of 2 +/- 1% (SE) to 50.0 +/- 0.1, 78 +/- 3, and 76 +/- 3% of total cardi ac output, respectively. Average cardiac index in the 20-, 18-, and 16 -gauge fistula animals increased by 105, 270, and 250%, respectively, compared with control. Right atrial pressure and heart weight were inc reased in proportion to the size of the fistula. MAP in the control an d 20-, 18-, and 16-gauge fistula animals was 122 +/- 5, 126 +/- 3, 118 +/- 3, and 111 +/- 4 mmHg, respectively. There were no significant di fferences in MAP or systemic flow among any of these groups. The calcu lated total peripheral resistance in all fistula groups was significan tly decreased compared with control. This study provides the quantitat ive information regarding the overall hemodynamic response to the open ing of differently sized fistulas in the rat. This information will be useful in the study of chronic congestive heart failure and volume-lo ading heart hypertrophy.